Some data-storage devices rely on ferromagnets — in which the neighbouring magnetic spins of atoms are aligned — to hold information as magnetic bits. However, magnetic fields can corrupt stored data. Antiferromagnets, in which the neighbouring spins are oppositely aligned, are not as sensitive to magnetic fields, so are a promising alternative. Sebastian Loth, Andreas Heinrich and their colleagues at IBM's Almaden Research Center in San Jose, California, have read and switched the magnetic states of antiferromagnetic iron atoms, demonstrating that information can be stored antiferromagnetically.

Credit: S. LOTH, IBM RESEARCH/ALMADEN

The authors placed a few antiferromagnetic iron atoms in a regular pattern (pictured) on a copper nitride surface, and switched their magnetic states by applying a current of more than 7 millivolts to individual atoms using the tip of a scanning tunnelling microscope. From images taken with the microscope, the authors could distinguish two stable and distinct magnetic states of the atoms.

Science 335, 196–199 (2012)